Conventionally, in relay systems of public telephone networks operated by telecommunication carriers, server operated by Internet service providers, and the like, according to a recipient identifier capable of uniquely identifying a recipient, communication between a communication terminal of the recipient (a recipient terminal) and a communication terminal of an arbitrary sender (a sender terminal) is established.
When an arbitrary sender designates a recipient identifier, which is capable of uniquely identifying a recipient like a telephone number or a mail address, in a sender terminal and informs a relay system of the recipient identifier, the relay system specifies a recipient based on this recipient identifier and establishes communication between the sender terminal and the recipient terminal (note that “establishment of communication” in this context includes every meaning like setting of a real time communication path between communication terminals and transmission of a mail or data from one communication terminal to the other communication terminal).
Usually, as the recipient identifier, one recipient identifier is basically given for one line or one recipient from the relay system. The recipient directly informs people who desire to send mails to the recipient (senders) like relatives, acquaintances, and customers of this recipient identifier in advance or notifies the senders of recipient identifier with various means like telephone, facsimile, letter, and electronic mail (see, for example, Japanese Patent Application Laid-Open No. H10-198613).
Incidentally, when the recipient enters a prize contest or applies for mail order, the recipient may notify the recipient identifier as a contact address. Such an act of the recipient himself/herself is likely to reveal the recipient identifier to a third party with whom the recipient does not wish to communicate.
When the recipient identifier is revealed to such a third party once, unsolicited telephone calls and unsolicited bulk emails for the purpose of sales and solicitation are frequently sent to the recipient. The recipient identifier is often used for purposes that are not expected by the recipient. Practically, this makes it impossible to use the line and the mail address.
In such a case, the recipient abandons this recipient identifier and acquires a new recipient identifier from the relay system. However, the recipient has to inform plural senders, who desire to send mails to the recipient, of a change of the contact address to the new recipient identifier. This requires a lot of time and labor of the recipient.
It is an object of the present invention to solve such conventional problems and provide a communication method, a communication system, a relay system, a communication program, a program for the relay system, a mail delivery system, a mail delivery method, and a mail delivery program that can prevent a recipient identifier from being used for purposes that are not expected by a recipient.